During a medical procedure it is desired to precisely and securely position and support a medical device in a fixed location relative to the patient. For example, during medical procedures that require access to the cranial cavity an external anchoring system is affixed to the skull. This anchoring system creates a fixed point of reference relative to the patient, thereby allowing for a higher degree of control and precision during a medical procedure. In addition, the anchoring system allows the medical device to access a location within a patient while maintaining operational control external to the patient. The anchoring system is attached to the skull by fasteners and includes a channel that accesses a bore in the skull. The channel can accommodate instruments such as a surgical probe or endoscope.
Existing cranial anchoring systems are secured to the skull by conventional methods such as the use of bone screws. While providing secure anchoring to the cranium is important, it is less than optimal to inflict any more trauma than is necessary to the skull during a procedure. For example, U.S. Pat. No. 8,845,655 describes a guide instrument that is placed over a burr hole in a patient's skull to enable operation on the patient's brain. Screws are employed to secure the base plate to the skull of a patient. The guide instrument requires multiple bone fixation screws to be placed in the patient's skull. This assembly increases the time it takes to position and attach the instrument and to remove the instrument from the patient. As a result, the patient's skull not only has a burr hole drilled therein, but must receive additional trauma from threaded bone fixation screws.